Add support for additional blend modes to SVGFEBlendElement

New modes to be supported are:

  overlay,
  color-dodge,
  color-burn,
  hard-light,
  soft-light,
  difference,
  exclusion,
  hue,
  saturation,
  color and
  luminosity

Since the new modes don't have any corresponding IDL constants exposed
on the SVGFEBlendElement interface, a mechanism is added to be able to
differentiate between "internal" and "exposed" enumeration values, and
reject those that are "internal-only" from being read or written
through SVGAnimatedEnumeration.

Test feBlend-all-modes.html evolved from test in WebKit commit
http://trac.webkit.org/changeset/170433 by Dirk Schulze.

BUG=389594

Review URL: https://codereview.chromium.org/447193002

git-svn-id: svn://svn.chromium.org/blink/trunk@179732 bbb929c8-8fbe-4397-9dbb-9b2b20218538
diff --git a/third_party/WebKit/LayoutTests/TestExpectations b/third_party/WebKit/LayoutTests/TestExpectations
index 7b2faf1..7c69def 100644
--- a/third_party/WebKit/LayoutTests/TestExpectations
+++ b/third_party/WebKit/LayoutTests/TestExpectations
@@ -1269,6 +1269,7 @@
 crbug.com/392706 virtual/threaded/animations/play-state-initially-paused.html [ Failure ]
 
 crbug.com/399459 http/tests/misc/link-rel-prefetch-and-subresource.html [ Pass Failure ]
+crbug.com/389594 svg/filters/feBlend-all-modes.html [ NeedsManualRebaseline ]
 
 # V8 3.28.19
 crbug.com/392762 fast/js/nested-object-gc.html [ Pass Crash ]